Generally, in a power semiconductor module for use in a vehicular inverter circuit and/or relay circuit, a large current flows and the amount of heat generation is large; and therefore, countermeasures against heat dissipation are required while securing electrical insulation properties.
Consequently, in a conventional semiconductor device of Patent Document 1, there is disclosed that a plurality of semiconductor chips are directly arranged on a conductive heat dissipation substrate and these components are integrally formed inside a resin package by transfer mold molding together with a plurality of external connection electrodes electrically connected to the semiconductor chips (for example, see Patent Document 1). In this case, the resin package on the surface side opposite to the surface of the heat dissipation substrate on which the plurality of the semiconductor chips are arranged is thin; heat emitted from the semiconductor chips passes through the heat dissipation substrate and then further passes through the thin resin package to be dissipated to a heat sink or the like attached to the outside of the power semiconductor module. Incidentally, the power semiconductor module and the heat sink are bonded via heat dissipating insulation adhesive or the like.